Cutting inserts and holders for such cutting inserts, particularly for cutting metal, are known in the art. Such cutting inserts and holders, also known as cutting tools, are commonly used for rotary cutting operations such as drilling, milling, and the like.
For example, rotary cutting tools for milling a 90° shoulder in a workpiece are known. Such tools are generally designed to hold cutting members having a lateral cutting edge which generates a cylindrical or substantially cylindrical envelope of revolution which is substantially parallel to the rotary axis of the cutting tool and thus being capable of milling a 90° shoulder in a workpiece.
When using such cutting inserts or cutting tools under demanding machining conditions, however, stability issues may arise due to the great magnitude of cutting forces which may potentially be created by the demanding conditions of the cutting process. In particular, the cutting forces of the rotary cutting tool described above include a sum total of a torque of each cutting insert generated while milling the workpiece, the torque being the product of cutting forces acting on each cutting edge portion and a radius of the cylindrical envelope of revolution of each cutting edge portion. Thus, employing lateral cutting edges of the cutting tool translates into greater magnitude of cutting forces as compared to employing, for example, face cutting edges. Furthermore, there may be an excessive load on, and/or vibrations of, the cutting members and/or cutting tool. Moreover, damages to the machined surface of a workpiece may occur. These issues may limit the use of conventional cutting members and/or cutting tools.
Accordingly, in order to facilitate cutting even when demanding conditions exist, cutting members have been designed for rapid removal of large amounts of material on a workpiece. In such machining operations, while the depth of a cut may potentially be shallow, e.g., up to 2 mm, the lateral feed rate is very high, e.g., up to 3-4 mm per tooth of the cutter. Such inserts are very effective for rough machining, e.g., of what may be called “tubs”, i.e., deep pockets formed in a solid metal workpiece as may be customary in, for example, the die and mold manufacturing industry. The main cutting edge of such cutting members may be disposed adjacent the face of the cutting tool and may potentially extend transversely to the axis of rotation of the cutting tool.
It is known that in order to facilitate cutting even when demanding conditions exist, a longitudinal edge of the cutting insert may potentially be relieved from a sidewall of the machined workpiece, to relieve excess load on, and/or vibrations of, the cutting tool. To achieve this, it is known to design a special tool with tilted insert pockets, so that cutting inserts positioned in such specially-manufactured, tilted pockets will have a lateral edge thereof relieved from the sidewall of the workpiece.
From U.S. Pat. No. 5,052,863 there is known, for use in a peripheral rotary milling cutter having a cylindrical holder and at least one replaceable, peripherally disposed cutting insert, a cutting insert is formed with its lateral cutting edge being curved and forming part of the curved side of a slanted plane which intersects a cylinder constituting a surface of revolution of said lateral cutting edge at an angle corresponding to the axial rake of the lateral cutting edge in cutting member which is mounted in the milling cutter.
From U.S. Pat. No. 5,071,292 there is known, for use in a peripheral rotary milling cutter having a cylindrical holder and at least one replaceable, peripherally disposed cutting insert, a cutting insert being formed with cutting rake and the relief flank surfaces that are continuously curved so that the insert rake and relief angles as defined with respect to the cylindrical holder remain substantially invariant along the length of the cutting edge.
From U.S. Pat. No. 5,078,550 there is known, for use in a peripheral rotary milling cutter having a cylindrical holder and at least one replaceable, peripherally disposed cutting insert, having a side relief flank that comprises first and second component side relief surfaces intersecting at an intersection line extending along the side relief flank from a first position adjacent a leading end of the insert and located at an intermediate position thereof to a second position intersecting said cutting edge and adjacent a trailing end of the insert, said component flank surfaces being substantially planar and being angularly disposed with respect to one another so that an insert side relief angle as defined with respect to the cylindrical holder in the region of the leading end substantially equals an insert side relief angle in the region of the trailing end.
From U.S. Pat. No. 5,145,295 there is known, for use in a peripheral rotary cutter having a cylindrical holder and at least one replaceable, peripherally disposed cutting insert, a cutting insert being formed with a relief flank surface comprising a first portion defined between said cutting edge and an intermediate portion of said relief flank surface and a second portion defined between said intermediate portion and the base of the insert, said first portion presenting a first relief flank angle, said second portion presenting a second relief flank angle, said relief flank angel being significantly greater than said second relief flank angle when said intermediate portion which bridges said first and second portions being directed transversely with respect to said first and second portions.
From U.S. Pat. No. 5,207,538 there is known, for use in a peripheral rotary milling cutter having a cylindrical holder in at least one replaceable peripherally disposed cutting insert, a cutting insert being formed with a relief flank surface comprising a first portion defined between said cutting edge and an intermediate portion of said relief flank surface and a second portion defined between said intermediate portion and the base of the insert, said first portion presenting a first relief flank angle, said second portion presenting a second relief flank angle, said first relief flank angle being significantly greater than said second relief flank angle when said intermediate portion which bridges said first and second portions being directed transversely with respect to said first and second portions.
As can be seen, e.g., in FIG. 14 of U.S. Pat. No. 5,207,538 and U.S. Pat. No. 5,145,295, the respective cutting inserts may be mounted in a holder so that a lateral cutting edge is parallel to the axis of rotation of the rotary milling cutter for machining a 90° shoulder in a workpiece.
U.S. Pat. No. 4,708,537 discloses a metal cutting tool having an exchangeable cutting insert mounted on a replaceable cartridge seat releasably fitted in a holder of the cutting tool and particularly, inserts clamped in the respective cutting tool are positioned to provide a lateral cutting edge being parallel to the axis of rotation of the rotary cutting tool in order to allow milling of a 90° shoulder in a workpiece.
European patent application 1 075 889 relates to a rotary cutting tool having at least one indexable insert wherein the insert has a main cutting edge and an outer peripheral cutting edge. Said main cutting edge is disclosed as being inclined at a cutting edge angle and as being shaped like an arc or a substantially arc wherein said outer peripheral cutting edge is shaped like a straight line, an arc, or a substantially arc, so as to be back-tapered with respect to the center axis of tool. The respective arrangement is discussed as suppressing chattering-vibration and as realizing a stable and high efficiency working.
U.S. patent application Ser. No. 5,460,464 refers to a cutting insert comprising lateral cutting edge ridges being inclined by an angle and front cutting edge ridges being inclined as an angle vis-à-vis a rectangular base shape.